1. Field of the Invention
This invention relates to electronic circuit packages having a resinous layer filled into gaps between a circuit substrate and electronic circuit elements bonded onto the circuit substrate.
2. Description of the Prior Art
In an electronic circuit package of a high integration density such as a large scale integrated circuit, it is important to ensure the dissipation of heat which is to be generated from the electronic circuit elements incorporated into the package upon the application of power to the circuit. It is also important that, in the case where failure of an electronic circuit element mounted on a circuit substrate is found during production of such an electronic circuit package, for example, during product testing, the defective element can easily be removed from the circuit substrate and replaced by a new element. This is because elements and substrates for use in such an electronic circuit package are, in general, expensive and, thus, it is very uneconomical to discard the entire package containing the non-defective elements and the substrate only because of one or a few defective elements.
It is known that, in order to protect the electronic circuit elements against moisture or to accelerate the dissipation of heat from the electronic circuit elements, a silicone resin is filled into gaps between the circuit substrate and the electronic circuit elements or the electronic circuit elements are encapsulated by a silicone resin (see, for example, IEEE TRANSACTIONS ON PARTS, HYBRIDS, AND PACKAGING, Vol. PHP-12, No. 3, Sept. 1976, PP 182-187). However, the silicone resin may sometimes impart insufficient moist heat resistance to the resulting package. Further, in the case where the applied silicone resin is completely cured, it may become impossible to replace defective elements by new ones.